src/java.base/share/classes/java/lang/String.java

rev 58157 : 8240094: Optimize empty substring handling
Reviewed-by: redestad, igerasim, jlaskey
Contributed-by: sergei.tsypanov@yandex.ru

*** 1817,1827 ****
       * is the string being searched for.
       *
       * @param   src         the characters being searched.
       * @param   srcCoder    coder handles the mapping between bytes/chars
       * @param   srcCount    count of the source string.
!      * @param   tgt         the characters being searched for.
       * @param   fromIndex   the index to begin searching from.
       */
      static int lastIndexOf(byte[] src, byte srcCoder, int srcCount,
                             String tgtStr, int fromIndex) {
          byte[] tgt = tgtStr.value;
--- 1817,1827 ----
       * is the string being searched for.
       *
       * @param   src         the characters being searched.
       * @param   srcCoder    coder handles the mapping between bytes/chars
       * @param   srcCount    count of the source string.
!      * @param   tgtStr      the characters being searched for.
       * @param   fromIndex   the index to begin searching from.
       */
      static int lastIndexOf(byte[] src, byte srcCoder, int srcCount,
                             String tgtStr, int fromIndex) {
          byte[] tgt = tgtStr.value;
*** 1898,1911 ****
       *             {@code endIndex}.
       */
      public String substring(int beginIndex, int endIndex) {
          int length = length();
          checkBoundsBeginEnd(beginIndex, endIndex, length);
-         int subLen = endIndex - beginIndex;
          if (beginIndex == 0 && endIndex == length) {
              return this;
          }
          return isLatin1() ? StringLatin1.newString(value, beginIndex, subLen)
                            : StringUTF16.newString(value, beginIndex, subLen);
      }
  
      /**
--- 1898,1911 ----
       *             {@code endIndex}.
       */
      public String substring(int beginIndex, int endIndex) {
          int length = length();
          checkBoundsBeginEnd(beginIndex, endIndex, length);
          if (beginIndex == 0 && endIndex == length) {
              return this;
          }
+         int subLen = endIndex - beginIndex;
          return isLatin1() ? StringLatin1.newString(value, beginIndex, subLen)
                            : StringUTF16.newString(value, beginIndex, subLen);
      }
  
      /**